ALTER STREAMING TABLE

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Applies to: Databricks SQL

Allows you to either:

• Add a schedule for refreshing an existing streaming table.
• Alter an existing refresh schedule for a streaming table.
• Drop the refresh schedule for a streaming table. If the schedule is dropped, the object needs to be refreshed manually to reflect the latest data.

To add or alter a comment on a table or its columns, use COMMENT ON.

Syntax

ALTER STREAMING TABLE table_name
  {
    { ADD | ALTER } SCHEDULE [ REFRESH ] schedule_clause |
    DROP SCHEDULE |
    ALTER COLUMN clause |
    SET ROW FILTER clause |
    DROP ROW FILTER |
    SET TAGS clause |
    UNSET TAGS clause |
  }

  schedule_clause
  { EVERY number { HOUR | HOURS | DAY | DAYS | WEEK | WEEKS } |
    CRON cron_string [ AT TIME ZONE timezone_id ] }

Parameters

• table_name

  The name of the streaming table to alter the definition of. The name must not include a temporal specification.

• SCHEDULE [ REFRESH ] schedule_clause

  Allows you to add a schedule to or alter the schedule of a streaming table.

  • EVERY number { HOUR | HOURS | DAY | DAYS | WEEK | WEEKS }

    To schedule a refresh that occurs periodically, use EVERY syntax. If EVERY syntax is specified, the streaming table or materialized view is refreshed periodically at the specified interval based on the provided value, such as HOUR, HOURS, DAY, DAYS, WEEK, or WEEKS. The following table lists accepted integer values for number.

    Time unit	Integer value
    HOUR or HOURS	1 <= H <= 72
    DAY or DAYS	1 <= D <= 31
    WEEK or WEEKS	1 <= W <= 8

    注記

    The singular and plural forms of the included time unit are semantically equivalent.

  • CRON cron_string [ AT TIME ZONE timezone_id ]

    To schedule a refresh using a quartz cron value. Valid time_zone_values are accepted. AT TIME ZONE LOCAL is not supported.

    If AT TIME ZONE is absent, the session time zone is used. If AT TIME ZONE is absent and the session time zone is not set, an error is thrown. SCHEDULE is semantically equivalent to SCHEDULE REFRESH.

• ALTER COLUMN

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  Changes a property of a column.

• SET ROW FILTER clause

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  Adds a row filter function to the streaming table. All subsequent queries to the streaming table receive a subset of the rows where the function evaluates to boolean TRUE. This can be useful for fine-grained access control purposes where the function can inspect the identity or group memberships of the invoking user to determine whether to filter certain rows.

• DROP ROW FILTER

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  Drops the row filter from the streaming table, if any. Future queries return all rows from the table without any automatic filtering.

• SET TAGS ( { tag_name = tag_value } [, ...] )

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  Apply tags to the streaming table. You need to have APPLY TAG permission to add tags to the streaming table.

  • tag_name

    A literal STRING. The tag_name must be unique within the streaming table or column.

  • tag_value

    A literal STRING.

• UNSET TAGS ( tag_name [, ...] )

  Preview

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  Remove tags from the streaming table. You need to have APPLY TAG permission to remove tags from the streaming table.

  • tag_name

    A literal STRING. The tag_name must be unique within the streaming table or column.

Examples

SQL

-- Adds a schedule to refresh the streaming table once a day
-- at midnight in Los Angeles
> ALTER STREAMING TABLE my_st
  ADD SCHEDULE CRON '0 0 0 * * ? *' AT TIME ZONE 'America/Los_Angeles';

-- Alters the schedule to run every 15 minutes for a streaming table
> ALTER STREAMING TABLE my_st
  ALTER SCHEDULE EVERY 15 MINUTES;

-- Drops the schedule for a streaming table
> ALTER STREAMING TABLE my_st
  DROP SCHEDULE;

Related articles

• COMMENT ON
• CREATE STREAMING TABLE
• TIME ZONE management